Physicochemical and biological evaluation of siRNA polyplexes based on PEGylated Poly(amido amine)s.

Purpose: Use of RNA interference as novel therapeutic strategy is hampered by inefficient delivery of its mediator, siRNA, to target cells. Cationic polymers have been thoroughly investigated for this purpose but often display unfavorable characteristics for systemic administration, such as interactions with serum and/or toxicity.

Methods: We report the synthesis of a new PEGylated polymer based on biodegradable poly(amido amine)s with disulfide linkages in the backbone.

Improved synthesis strategy of poly(amidoamine)s for biomedical applications: catalysis by "green" biocompatible earth alkaline metal salts.

Poly(amidoamine)s (PAAs) have received significant attention due to their good biocompatibility and fast biodegradation profile which gives these polymers high potential in biomedical applications. Conventional synthesis of PAAs via aza-type Michael addition reaction of primary amines to bis-acrylamides often proceeds slowly and takes several days, which does not allow fast and extensive screening of PAA libraries for their bioactivity. Current investigation was dedicated to the development of catalytic synthesis procedures in order to decrease the polymerization times.

Flotillin-dependent endocytosis and a phagocytosis-like mechanism for cellular internalization of disulfide-based poly(amido amine)/DNA polyplexes.

Extensive research is currently performed on designing safe and efficient non-viral carriers for gene delivery. To increase their efficiency, it is essential to have a thorough understanding of the mechanisms involved in cellular attachment, internalization and intracellular processing in target cells. In this work, we studied in vitro the cellular dynamics of polyplexes, composed of a newly developed bioreducible poly(amido amine) carrier, formed by polyaddition of N,N-cystamine bisacrylamide and 1-amino-4-butanol (p(CBA-ABOL)) on retinal pigment epithelium (RPE) cells, which are attractive targets for ocular gene therapy.

Disulfide-based poly(amido amine)s for siRNA delivery: effects of structure on siRNA complexation, cellular uptake, gene silencing and toxicity.

Purpose: RNA interference (RNAi) is a process by which small interfering RNAs (siRNA) induce sequence-specific gene silencing. Therefore, siRNA is an emerging promise as a novel therapeutic. In order to realize the high expectations for therapeutic applications, efficient delivery systems for siRNA are necessary.

A method for quantifying cellular uptake of fluorescently labeled siRNA.

Efficient intracellular delivery of siRNA is a significant hurdle to its therapeutic success. For biological studies on the efficiency of carrier-mediated uptake of siRNA, quantitative determination of the amount of internalized siRNA is required. In this study, when the apparent uptake of fluorescently labeled siRNA, formulated in different lipo- and polyplexes, was examined using different techniques, major differences were observed.

Shielding the cationic charge of nanoparticle-formulated dermal DNA vaccines is essential for antigen expression and immunogenicity.

Nanoparticle-formulated DNA vaccines hold promise for the design of in vivo vaccination platforms that target defined cell types in human skin. A variety of DNA formulations, mainly based on cationic liposomes or polymers, has been investigated to improve transfection efficiency in in vitro assays. Here we demonstrate that formulation of DNA into both liposomal and polymeric cationic nanoparticles completely blocks vaccination-induced antigen expression in mice and ex vivo human skin.

A newly developed chemically crosslinked dextran-poly(ethylene glycol) hydrogel for cartilage tissue engineering.

Cartilage tissue engineering, in which chondrogenic cells are combined with a scaffold, is a cell-based approach to regenerate damaged cartilage. Various scaffold materials have been investigated, among which are hydrogels. Previously, we have developed dextran-based hydrogels that form under physiological conditions via a Michael-type addition reaction.

Rapidly in situ-forming degradable hydrogels from dextran thiols through Michael addition.

Thiol-functionalized dextrans (dex-SH) (M(n,dextran) = 14K or 31K) with degrees of substitution (DS) ranging from 12 to 25 were synthesized and investigated for in situ hydrogel formation via Michael type addition using poly(ethylene glycol) tetra-acrylate (PEG-4-Acr) or a dextran vinyl sulfone conjugate with DS 10 (dex-VS DS 10). Dex-SH was prepared by activation of the hydroxyl groups of dextran with 4-nitrophenyl chloroformate and subsequent reaction with cysteamine. Hydrogels were rapidly formed in situ under physiological conditions upon mixing aqueous solutions of dex-SH and either PEG-4-Acr or dex-VS DS 10 at polymer concentrations of 10 to 20 w/v%.